Chemically amplified photoresist compositions generate an acid upon irradiation with e.g., a far ultraviolet ray typified by a KrF excimer laser beam (wavelength: 248 nm), an ArF excimer laser beam (wavelength: 193 nm) and the like, or an electron beam at a light-exposed site, and chemical reactions catalyzed by the acid cause a difference of the rate of dissolution of the light-exposed site and a light-unexposed site in a developer solution, thereby enabling a resist pattern to be formed on a substrate.
For the photoresist compositions, superior resolving ability and a superior pattern configuration have been demanded with the advance of microfabrication technologies. To address the demand, a variety of acid generating agents to be incorporated into a photoresist composition have been investigated; for example, a sulfonic acid salt having a bulky group, and the like have been developed (see Japanese Unexamined Patent Application, Publication Nos. 2004-307387 and 2007-145797).
However, in these days when further miniaturization of resist pattern is advancing, levels of performances expected for resist patterns are further elevated, and conventional photoresist compositions fail to sufficiently satisfy the resolving ability, an LWR (Line Width Roughness) performance, which is an indicative of a variation in the line width, and the like.